Steel pipe is typically manufactured at a mill one batch at a time commonly referred to as a heat. A single ladle of molten steel is used to form a slab or billet for a single heat. The slab or billet is then divided into smaller units commonly referred to as coils. Finally, each coil is further divided into several lengths or individual sections of pipe commonly referred to as joints. Therefore, each section of pipe can be uniquely identified by specifying the heat, coil and joint.
After pipe joints are manufactured, they are subjected to various tests prior to shipment. Pipe joints are then shipped to purchasers who receive the pipe and decide whether to accept it. Purchasers sometimes perform additional testing on pipe joints before they are accepted. After pipe joints are accepted, they are either stored for future use or installed directly in a pipeline or well bore. Accurate record keeping at each of these phases in the manufacturing process is essential to be able to accurately identify individual pipe joints for future operations.
In one known method of identifying pipe joints, each pipe joint is stenciled with identification information. This method of identifying pipe joints is subject to significant shortcomings, in some cases, because pipe joints are subjected to other processing that tends to remove stenciled information. Examples of these processes are internal or external coating, hot or cold bending, threading or grit blasting. The coating process typically removes the stencils. After coating, each pipe joint has to be re-stenciled. Thus, the possibility for error because of failure to re-stencil pipe joints with the correct information exists. Stenciled information also has a useful life of about six months. Therefore, stenciled information is not useful for long-term identification of pipe joints. Furthermore, stenciled information cannot be read at all after the pipe joint is deployed in a pipeline and buried or submerged in water.
In another known method of identifying pipe joints, a bar code label that embodies manufacturing information and identification information is disposed inside of each pipe joint. The bar code label remains in the pipe joint throughout its lifetime and is readable from either inside or outside the pipe joint. This method of identifying pipe joints is not effective because the bar code labels cannot be read accurately using existing technology. Scanning devices known in the art as "pigs" are deployed into completed pipelines to read the bar code labels with generally poor results. It is also undesirable in many cases to leave bar code labels inside pipe joints because the inside of the pipe joints must be scraped clean prior to installation. The use of bar coded labels inside pipe joins also leads to the possibility of valve jams and similar problems that occur because the bar code labels tend to loosen and become dislodged over time as fluid flows in the completed pipeline.
Paper records known in the art as tally sheets have been used to keep track of pipe joints at various stages of manufacturing, testing and shipping. Shortcomings in prior art pipe joint identification methods result in problems in maintaining accurate tally sheets. Specifically, prior art methods of identifying pipe joints are cumbersome, inefficient and subject to human error. These potentials for error are compounded by the manual labor intensive nature of creating tally sheets.
Impending Federal Department of Transportation regulations mandate that each section of pipe be uniquely identified and its manufacturing history recorded and saved. By continuing to use the typical manual labor intensive procedures for identifying each section of pipe and recording its history, these regulations will lead to more elaborate but still error-prone record keeping procedures on the part of manufacturers and users of steel pipe.
Another continuing problem in the field has been the difficulty of maintaining accurate testing, transportation and shipping records for pipe joints. This is true because the homogeneous nature of pipe joints makes it difficult to uniquely identify a specific joint. Moreover, steel pipe joints of similar grade have substantially similar characteristics regardless of where or by whom they were manufactured.
The ability to maintain accurate identification information for pipe joints is also desirable because catastrophic failure of pipe joints can result in legal liability for the owner of the pipe. If the pipe owner has evidence identifying the manufacturer of the pipe, the pipe owner has the opportunity to seek legal recourse against that manufacturer to limit his liability. Accurate identification information further allows the pipe owner to inspect pipe joints with similar histories (e.g. pipe joints from the same heat and/or coil) to prevent further catastrophic failures.
A method of creating a comprehensive manufacturing, shipping and location history for pipe joints is desirable. Such a method would result in simplified record keeping procedures and assist users of steel pipe joints in their duty of compliance with new government regulations. A method of creating a comprehensive manufacturing, shipping and location history would also allow substantial time savings in pipe shipping and receiving operations and allow accurate identification of installed pipe joints.